The present invention relates to a submarine storage facility for liquified energy gases, and more particularly to a pressure transfer storage facility resting on the seabed at considerable depth wherein ambient seawater pressure at that depth is available for transfer to the material stored in the facility to promote and maintain liquified state thereof.
While liquified energy gases have been known for many years, until recently the extreme hazards presented in the handling and storage of such materials have impeded usage thereof and the concomitant development of suitable storage facilities and handling techniques. While the hazards from these liquified energy gases are no less today than in earlier times, the present widespread demand for energy, along with shrinking developed worldwide crude oil reserves, has created a need for storage facilities for more plenteous energy gases stored in cryogenically cooled and liquified state. At the same time public clamor for a safe and non-hazardous, non-polluted environment has militated against any widespread onshore storage facilities development, particularly in the more densely populated areas.
The ocean environment is a particularly attractive one for liquified energy gas facilities. Its isolation from population centers reduces the potential for loss of life and property. Its capacity to dissipate methane, leaking naturally from substantial depths, further reduces surface fire hazards. Its capacity to distribute shockwaves from bombs and seismic activity evenly to marine structures by hydraulic action reduces risks of structural failures otherwise obtaining in e.g. land based facilities. Finally, the ambient pressure available at substantial depths, such as at 200 meters, along with the absence of interfering marine life forms at that depth have suggested an almost ideal environment for submerged liquified energy gas storage facilites embodying the invention herein which rest upon, but are not necessarily anchored to, the seadbed.
While seabased storage facilities have been proposed in the prior art, floating surface facilities have the inherent drawback that pitching and rolling with wave action generates tremendous thermal gradients within the storage vessels and promotes unwanted regassification of the stored material. Stable storage facilities resting on the seabed in accordance with the present invention minimize these drawbacks. Use of effectively insulated rigid structure for transfer of ambient deep seawater pressure, rather than thin flexible large area membranes with organic balancing fluids to dissipate the extreme thermal gradient as has been proposed in the prior art, also reduces the thermal gradient strain and regassification tendency.
One object of the present invention is to provide a new and improved deepwater submarine storage facility for liquified gases, such as LNG.
Another object of the present invention is to apply deepwater ambient pressure to stored liquified gases to promote and maintain liquified state thereof.
A further object of the present invention is to provide a deepwater submarine storage facility for liquified gases which rests in a stable operating state upon the seabed.
Yet another object of the present invention is to provide a storage facility which will achieve the foregoing objects, efficiently, effectively, reliably and economically.
These objects are achieved by a submarine storage facility for cryogenically cooled and liquified energy gases and the like which operates offshore at a substantial depth, such as eg. 200 meters. The structure thereof includes an insulated container with a conduit leading therefrom, for introduction and removal of liquified material. A piston action provided by structure of the container transfers a controlled pressure derived from ambient water at the depth of the seabed to the stored liquified material in order to promote and maintain its liquid state throughout storage and handling. Pressure varying means to apply a selected fraction of available pressure, and ballasting means to float the structure to the surface for loading, transport, maintenance, inspection and the like are other related aspects of the present invention.
These and other objects, advantages and features will be apparent to those skilled in the art from consideration of the following detailed description of preferred embodiments presented in conjunction with the accompanying drawing.